Process of producing nitrocellulose and a blasting explosive containing same



I Patented May 22, 195i PROCESS OF PRODUCING NITROCELLU- LOSE AND A BLASTING EXPLOSIVE CONTAINING SAME Stanley Fordham, Saltcoats, Scotland, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain N Drawing. Application February 3, 1947, Se-

rial No. 726,226. 1946 r 9 Claims. 1

The present invention relates to the production of nitrocellulose and is particularly concerned with the production of nitrocellulose soluble in nitroglycerine and of gelatinous explosives therefrom.

The object of the present invention is to provide a nitrocellulose soluble in nitroglycerine which can be dissolved more easily in nitroglycerine than heretofore thereby to produce gelatinous explosives of improved uniformity.

According to the present invention in a process for the production of nitrocellulose soluble in nitroglycerine the improved method includes the steps of finally washing the nitrocellulose with an aqueous composition of an organic compound having a long carbon chain of open or closed structure which is a liquid or soft solid capable of remaining substantially unvolatilised during the drying of the nitrocellulose, is soluble or dispersible in nitroglycerine, but which is a nonsolvent for nitrocellulose, and drying the thus treated product by mechanically removing any of the liquor expressible therefrom by centrifuging or pressing and then evaporating water from the resulting damp product.

The said organic compound is also preferably a non-accelerant of the rate of solution of the nitrocellulose in nitroglycerine.

By the term long carbon chain is meant a carbon chain of at least eight carbon atoms.

According to the present invention the process for the production of gelatinous explosives comprises finally washing nitrocellulose soluble in nitroglycerine with an aqueous composition of an organic compound as hereinbefore defined, drying the thus treated product by mechanically removing any of the water expressible therefrom by centrifuging or pressing and then evaporating water from the resulting damp nitrocellulose, and thereafter mixing the dry nitrocellulose with one or more liquid explosive nitric esters.

By the term nitroglycerine is meant nitroglycerine itself, and low-freezing mixtures based on it Well known in the art.

The invention has been found particularly useful for finely pulped and quick gelatinising nitrocelluloses. These nitrocelluloses in particular if not treated according to the invention tend to go into solution in nitroglycerine in a nonuniform manner and this non-uniformity of the solution can be recognised by the naked eye whereas when these nitrocelluloses are treated according to the invention uniform solutions are produced. Heretofore it has been a common practice to blend dry nitrocellulose with inert In Great Britain March 14,

material in order to obtain the desired uniformity of distribution of the nitrocellulose in nitroglycerine but the blending of dry nitrocellulose with inert material is a dangerous and inconvenient operation which becomes unnecessary when the dry nitrocellulose is prepared according to the present invention.

Examples of organic compounds as herein defined that are liquids and are non-wetting agents are rosin oil, shale oil, and castor oil. These are supplied as an emulsion in the final Wash water preferably at a concentration such that the dry nitrocellulose retains about 5% of its weight of the oil. Examples of organic compounds as hereindefined that are liquids and soft solids and Wetting agents are Turkey-red oil, sulphonated methyl oleate, and ethylene oxide condensation products of long chain alcohols or amides. The best results are obtained with highly sulphonated oils, employed dissolved in the final wash Water in such a concentration that'the dry nitrocellulose retains about 2% of its weight of the sulphonated oil.

Organic compounds as herein defined that are wetting agents give the most readily dispersed nitrocellulose, but those that are non-wetting liquids have the additional advantage of reducing the dustiness of the dry nitrocellulose, and thus making it safer to handle as Well as improving the uniformity of the gelatinous nitrocellulose explosive made from it. The preferred treatment is therefore to use a combination of the organic Wetting or non-wetting liquids and soft solids as herein defined in proportions such that about 1.5% and 3.5% respectively are retained by the dry nitrocellulose.

The invention is illustrated in the following examples in which the parts are parts by weight. Bythe term blasting soluble nitrocellulose used in the following examples is meant, the product obtained by the nitration of purified cotton cops by the pot process to a nitrogen content of 11.95 to 12.25% and which is at least soluble in a mixture of ether and alcohol (66 O. P.) in the proportion by volume of 2:1 and has a viscosity of to 300 c. g. s. units in solution of 3 gms. in 100 ml. acetone 95% at 20 C.

Example I A mechanically nitrated and finely pulped nitrocotton, having a nitrogen content of 11.99% and a viscosity of 64 c. g. s. units in a solution of 4 gms. in 95% acetone at 20 0., is finally washed with a 4% solution of sulphonated methyl oleate,

and centrifuged to a water content of 33%. The water is then evaporated from the resulting damp nitrocellulose. The resulting dry prepared nitrocotton, containing approximately 2% sulphonated methyl oleate, is mixed into blasting gelatine of the following composition:

Parts Nitroglycerin 91.4 Prepared nitrocotton 8.0 Calcium carbonate 0.6

The nitroglycerine is introduced into the bowl of a McRoberts mixer which is maintained at 55 C. by a hot water jacket. The nitrocotton and then the calcium carbonate are added, and the stirrers are rotated. After mixing for 5 minutes the explosive leaves the sides of the bowl, and after minutes lifts from the bottom of the pan and rises above the stirring arms. The explosive may then be cartridged by extrusion, and gives a cord with the rough surface which, as is well known in the art, is characteristic of a good blasting gelatine. This explosive is completely uniform.

The same nitrocotton, used in the same Way but without treatment with oil, gives an explosive which does not clear from the bottom of the pan during mixing for 20 minutes, and which on extrusion gives a smooth cord. This explosive is heterogeneous, and contains many pips of poorly gelatinised nitrocotton clearly visible to the naked eye.

Example II Blasting soluble nitrocellulose is washed finally with a 10% aqueous emulsion of rosin oil, and centrifuged or pressed to an emulsion content of 30% and dried off by evaporation. The resulting dried nitrocellulose contains about 5% rosin oil. Blasting soluble nitrocellulose treated in this Way is less dusty and more readily wetted by nitroglycerine than usual, and may be used for the manufacture of blasting explosives, as for example blasting gelatine of the following composition:

Parts Low-freezing nitroglycerine 91.2 Prepared nitrocellulose 8.2 Chalk 0.6

Every 5 parts of the low-freezing nitroglycerine contain l parts glycerol trinitrate with 1 part ethylene glycol dinitrate.

The ingredients are mixed by hand in a rubberlined box, and the jelly thus formed is allowed to stand for one hour. The jelly is then transferred to a McRoberts mixer, and mixed for 35 minutes at 35 C. The explosive thus obtained is completely homogeneous and on extrusion gives a rough cord.

Example III Blasting soluble nitrocellulose is washed finally with an aqueous emulsion of '7 rosin oil in a 3% solution of sulphonated methyl oleate, centrifuged to a water content of 35% and dried oh. by evaporation. Little or no preferential absorption occurs, so that the nitrocellulose contains after drying about 3.5% rosin oil and 1.5% sulphonated methyl oleate. This dried nitrocellulose has reduced dustiness, and is wetted very readily and uniformly by liquid nitric esters. It may be used in the manufacture of blasting explosives, as for example for Ammon gelatine dynamite of the following composition.

Parts Nitroglycerine 48.2 Liquid nitrobody' .8 Prepared nitrocellulose 2.3 Ammonium nitrate 42.2 Wood meal 5.5

The nitrocellulose and wood meal are placed in a wooden box, but are not mixed together. The nitroglycerine is then run in, and the whole mixed by hand. The liquid nitrobody is then added and mixed by hand. The jelly thus formed is allowed to stand for one hour or longer. It is'then transferred to a McRoberts mixer and the ammonium nitrate added. The explosive is mixed for 35 minutes at 20 C., and then cartridged by extrusion.

I claim:

1. A process for the production of an improved nitrocellulose soluble in nitroglycerine which includes the steps of washing the nitrocellulose with an aqueous composition comprising a non-wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of rosin oil, shale oil, and castor oil, and thereafter drying the thus washed nitrocellulose to remove only the water.

2. A process for the production of an improved nitrocellulose soluble in nitroglycerine which includes the steps of washing the nitrocellulose with an aqueous composition comprising a wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of Turkey-red oil, sulphonated methyl oleate, ethylene oxide condensation products of long chain alcohols, and ethylene oxide condensation products of long chain amides, and thereafter drying the thus washed nitrocellulose to remove only the water.

3. A process for the production of an improved nitrocellulose soluble in nitroglycerine which includes the steps of washing the nitrocellulose with an aqueous composition comprising a non-wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of rosin oil, shale oil, and castor oil, and a wetting agent selected from the group of long chain organic compounds having at least 3 carbon atoms consisting of Turkey-red oil, sulphonated methyl oleate. ethylene oxide condensation products of lOIlg chain alcohols, and ethylene oxide condensation products of long chain amides; and thereafter drying the thus washed nitrocellulose to remove only the water.

4. A process as set forth in claim 1 wherein sufficient non-wetting agent is present in the aqueous composition so that after drying the nitrocellulose, the non-wetting agent retained therewith comprises about 5% by weight of the dried nitrocellulose.

5. A process as set forth in claim 2 wherein suificient wetting agent is present in the aqueous composition so that after drying the nitrocellulose, the wetting agent retained therewith comprises about 2% by weight of the dried nitrocellulose.

6. A process as set forth in claim 3 wherein the non-wetting agent and the wetting agent present in the aqueous composition are suificient in amount so that after drying the nitrocellulose, the non-wetting agent and the wetting agent comprise 1.5% and 3.5%, respectively of the total weight of the dried nitrocellulose.

7. A process for the production of gelatinous blasting explosives which comprises finally washing nitrocellulose with an aqueous composition comprising a non-wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of rosin oil, shale oil, and castor oil, thereafter drying the thus washed nitrocellulose to remove only the water,

and mixing the dried nitrocellulose with at least one liquid explosive nitric ester.

8. A process for the production of gelatinous blasting explosives which comprises finally washing nitrocellulose with an aqueous composition comprising a wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of Turkey-red oil, sulphonated methyl oleate, ethylene oxide condensation products of long chain alcohols, and ethylene oxide condensation products of long chain amides, thereafter drying the thug washed nitrocellulose to remove only the water, and mixing the dried nitrocellulose with at least one liquid explosive nitric ester.

9. A process for the production of gelatinous blasting explosives which comprises finally washing nitrocellulose with an aqueous composition comprising a non-wetting agent selected from the group of lon chain organic compounds having at least 8 carbon atoms consisting of rosin oil, shale oil, and castor oil, and a wetting agent selected from the group of long chain organic compounds having at least 8 carbon atoms consisting of Turkey-red oil, sulphonated methyl oleate, ethylene oxide condensation products of long chain alcohols, and ethylene oxide condensation products of long chain amides; thereafter drying the thus washed nitrocellulose to remove only the water, and mixing the dried nitrocellulose with at least one liquid nitric ester.

STANLEY FORDHAMa REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 434,049 Maxim Aug. 12, 1890 2,213,255 Olsen Sept. 3, 1940 2,235,298 Olsen Mar. 18, 1941 2,288,799 Fordyce et a1 July 7, 1942 FOREIGN PATENTS Number Country Date 15,565 Great Britain of 1905 

1. A PROCESS FOR THE PRODUCTION OF AN IMPROVED NITROCELLULOSE SOLUBLE IN NITROGLYCERIEN WHICH INCLUDES THE STEPS OF WASHING THE NITROCELLULOSE WITH AN AQUEOUS COMPOSITION COMPRISING A NON-WETTING AGENT SELECTED FROM THE GROUP OF LONG CHAIN ORGANIC COMPOUNDS HAVING AT LEAST 8 CARBON ATOMS CONSISTING OF ROSIN OIL, SHALE OIL, AND CASTOR OIL, AND THEREAFTER DRYING THE THUS WASHED NITROCELLULOSE TO REMOVE ONLY THE WATER. 